DIGITAL TEXT 2023 | BINCY BIJU PHYSICAL SCIENCE

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2 THE NATIONAL ANTHEM Jana-gana-mana adhinayaka jaya he Bharatha-bhagya-vidhata, Punjab-Sindh-Gujarat-Maratha Dravida-Utkala-Banga Vindhya-Himachala-Yamuna-Ganga Uchchala-Jaladhi-taranga Tava subha name jage, Tava subha asisa mage, Gahe tava jaya gatha. Jana-gana-mangala-dayaka jaya he Bharatha-bhagya-vidhata, Jaya he, jaya he, jaya he, Jaya jaya jaya jaya he! PLEDGE India is my country. All Indians are my brothers and sisters. I love my country, and I am proud of its rich and varied heritage. I shall always strive to be worthy of it. I shall give my parents, teachers and all elders respect, and treat everyone with courtesy. To my country and my people, I pledge my devotion. In their well-being and prosperity alone lies my happiness.

3 PREFACE Dear students, You were provided with opportunities to observe your surroundings and engage in simple experiments and investigative activities in earlier classes. The classroom experience, undoubtedly, might have helped you to record the information systematically and assimilate ideas through discussion and analysis. While understanding the scientific approach, there should also be the attitude to take forward the skills to apply them in day-to-day life. Moreover, an eco-friendly perspective must be adopted too. All these, through direct experiences, inquiry, and understanding preferably. This textbook presents ideas in accordance with this.The National Qualifications Framework, the current relevance of Disaster Management and the possibilities of ICT have also been considered while modifying the textbook.Go ahead, thinking, asking questions, approaching ideas critically and quizzing with teachers and friends. Make learning a joyful experience.

4 CONTENTS SL NO TOPIC PAGE NO 1 INTRODUCTION 5 2 FUELS 7 FOSSIL FUELS 8 4 COAL 9 5 BIO GAS 11 6 FUEL EFFICIENCY 12 7 SOLAR ENERGY 15 8 WIND ENERGY 16 9 GEO-THERMAL ENERGY 17 10 NUCLEAR ENERGY 17 11 GREN ENERGY 19 12 ENERGY CRISIS 20

5 It is said that energy can neither be created nor destroyed; then how does an energy crisis occur? Are the existing energy resources adequate to meet our energy needs?Observe the figures given below. Pictures of Kochi, asit wasin oldendays and now, are given. What are the changes that have been taking place? Write them down. • Travel facilities − from motorcycle to metro train • Multi-storied buildings • Business centers ENERGY MANAGEMENT UNIT 1

6 • Population growth What difference would have been brought in energy consumption due tothese changes? What energy sources would have been used for this? List down the different forms of energy you use for various purposes from the time you wake up till you reach your school. ➢ Muscular energy - for different physical activities ➢ Chemical energy - for cooking ➢ ➢ From which sources are you getting these forms of energy? We use different forms of energy from physical to electrical energy. We get these forms of energy from differentsourceslike Sun, fuels and powerstations. Speed of travel and housing facilities had to be increased to keep up with human progress. Accordingly, we had to increase the facilities forindustries and allied fields. This made it inevitable to transform the availableenergy from different sourcestomany other suitable forms. When energy is transformed from one form to another, some part of it gets lost in other forms. Such a lossisthe main cause for an energy crisis. Different sources of energy are to be used for different activities. Judiciousand scientific use of different sources of energy without being wasted is a necessity of today. Let's examine different sources of energy. Different Sources of Energy

7 Fuels Probably heat might have been the first form of energy created by ancienthumans. Heat energy was formed from forest fires. Later men made heat energy again by burning firewood. Hence the first fuel might have been firewood itself. What are fuels? Fuels are substances that release plenty of heat energy on burning. The main source of energy that we make use of today are fuel. We usedifferent fuels for different purposes including for cooking in the kitchen. Which are those fuels? Classify them into solids, liquids and gases, and tabulate them. Solid Liquid Gas • • • • • • Do these fuels burn in a similar way? Let's do an experiment: Take three papers of the same size. Keep one stretched. Crumble thenext.Make the thirdpaperwet using water. Burn each of them over a candleflame using pincers. Compare the burning ofeach.

8 What are the conditions favorable for the complete combustion ofdifferent fuels? The solid fuels must be dry. Liquid fuels must evaporate easily. The ignition temperature should be attained. Fossil fuels Which are the fuels that are used in vehicles andindustries? Tabulate the category to which these fuels belong: Stretched paper Crumbled paper Wet paper Burns very well Smoke is formed COAL PETROLEUM NATURAL GAS Fossil fuels high pressure and high or renewed in proportion to sources.

9 Coal Coal is the most abundant fossil fuel on the earth. The maincomponent of coalis carbon. Based on the carbon content, itis classified into four groups peat, lignite, anthracite, andbituminous coal. When coal is distilled in the absence of air, the substances obtained are ammonia, coal gas, coal tar, and coke. ▪ Which are the products obtained from the fractional distillationof petroleum? ▪ Which isthe cooking gasthat we get in cylinders for domesticuse? ▪ How will you know ifthere is leakage in an LPG cylinder? L P G and Safety Have you ever noticed the expiry date marked on a cooking gas cylinder? This is marked on the top of the cylinder. If it is marked“A 24”, the A indicates the months from January to March, and 24indicates the year ( 2024) We can understand that this cylinder has a maturity period up to March 2024. If recorded as B, then it isfrom April to June, C denotes July to September, and D denotes from October to December. If the smell of LPG is felt then it means that there is at least 3% of LPG in the atmospheric air. Even the presence of 2% LPG in air can cause fire. LPG is denser thanair. If the smell of LPG is felt do not operate the electric switch. Ifthere is a fire due to leakage of LPG then due to the heat the cylinder/tanker

10 will also get heated. Owing to the excess heat, the LPG becomes gas and increases the pressure inside. The ability to expandis 250 times for the gaseous LPG. Therefore when LPG becomesgas, the container cannot accommodate the entire gas. This increases the pressure to a very high level causing a huge explosion. Thisisknown as BLEVE (Boiling Liquid Expanding Vapour Explosion). . ▪ Never switch on or switch off the electricity when there is a leakage ofLPG. Why? ............................................................................................................... ▪ If there is a leakage of LPG does it rise up or come down in theatmosphere? Why? ............................................................................................................... ............................................................................................................... ▪ If there is leakage of LPG it is mandatory to open the doors andwindows.Why? ............................................................................................................... If you are convinced that there is a gasleak, disconnect electricityfrom outside the home (switch off the main switches). Switch offthe regulator and shift the cylinder to an empty space. Keep thewindows and doors open. Request help from the Fire Force bycalling in the toll-free number 108. Well-trained rescue operatorscan put out the fire by covering the top end of the cylinder with wet sack to prevent contact with oxygen. If the fire isin a flat or theto the storyone should not try to escape using lifts. Only staircase should be used. Cover the nose and the mouth with softcloth to avoid the intake ofsmoke or gases. Find out the expiry date of the gas cylinder at your home or schooland record it in the science diary

11 Fossil fuels were formed over lakhs of years. Shouldn't we keepthem for future generations as well? Make posters and exhibit them at school showing that fossil fuels are precious and thatthey are to be used judiciously. Biomass From ancienttimes, we have been using firewood, dried cow dung,etc., as fuel. Since these fuels are obtained from plants and animals,they are known as bio-waste or biomass. The burning of such bio-wastes will be partial combustion. Haven't you seen bio-wastes dumped in public places? Don't youexperience a putrid smell, when you pass them by? Which are thegases responsible for this smell?Besides air pollution, what are the problems that may arise whengarbage is heaped? Discuss and record. Biogas When biowaste is deposited in a biogas plant in the absence of oxygen, biogas is formed by the action of bacteria. Its main constituents are methane and carbon dioxide. The slurry discharged from the biogas plant is good manure. When biomass is converted into biogas, not only a fuel of greater calorific value is obtained but atmospheric pollution is also minimized. Discussthe need for a biogas plant at home and prepare notes. Nobody realizes that the waste we throw indiscreetly on the waysideinvites contagious diseases. Though we are in the forefront regarding individualhygiene,weare farbehindin community hygiene. Organizea seminar in your PTA, describing the advantages of the effective utilization of domestic garbages.

12 Fuel Efficiency You are now familiar with different fuels. Is the heat released from each of them the same when burnt? Let'sexamine. Some of you may be using LPG in your houses. Whatistheweight ofthe LPG filled in the cylinderssupplied to your homes? ……………………………………………………………………………………….. Using this quantity of LPG for how many days can you cook? ……………………………………………………………………………………………………… Howmanydays canyoucookusing firewoodofthe sameweight? ………………………………………………………………………………………………………… What difference do you feel in the efficiency of these two fuels? …………………………………………………………………………………………………… Calorific value The amount of heat liberated by the complete combustion of1 kg of fuel isits calorific value. Its unit is kilojoule/kilogram. • Some fuels and their calorific values: Hydrogen-150000kJ/kg CNG − 50000 kJ/kg Dried cow dung − 60008000 kJ/kgLPG − 55000 kJ/kg Biogas − 30000 − 40000 kJ/kg Coal − 25000 − 33000 kJ/kg Petrol− 45000 kJ/kg Methane − 50000 kJ/kg

13 Based on its calorific value, which fuel can be considered asthe most efficient? ……………………………………………………………………………………………………… Hydrogen and Hydrogen fuel cell Hydrogenis a fuelwith the highest calorific value.Thisishighlyinflammable and explosive in nature. So it is difficult to store and transport it. We make use of hydrogen fuel cell to produce electricity by combining hydrogen and oxygen. • Which are the instances when hydrogen is used as fuel? …………………………………………………………………………………. • Why is hydrogen not used as a domestic fuel? ……………………………………………………………………………………. Now you know about different types of fuels and their calorificvalues. What are the propertiesthat a good fuel must have? ▪ Should be easily available. ▪ Should be of low cost. ▪ Should have a high calorific value ▪ Should cause minimum atmospheric pollution oncombustion. ▪ Should be easily storable. ▪ A liquid fuel must not evaporate quickly at ordinarytemperatures. ▪ ▪ ▪ ▪ Electrical energy isthe mostimportantform of energy. Itsspecialityisthatit can easily be converted into many other forms.

14 Have you ever thought howour lifewould be ifthere is no electricity? The amount of electrical energy received per person is a measure ofthe progress of the nation. You have already learned that we get electricity from a generator.Whatisthe energy conversion in a generator? • Fromwhere dowe getthe energy requiredfor theworkingofa generator? • Power stations are the centers where electricity is produced on a large scale for distribution. The mechanical energy required for running power generators is made available in different ways. Power stations can be classified based on the nature of the source providing the energy required to operate the generator. • Flowing water - hydroelectric power stations • • HYDROELECTRIC POWER STATIONS

15 Solar Energy We get different forms of energy from the Sun. Attempts are underway now to utilize solar energy to its maximum.What are the devices used for this? Discuss and expand the list. • Solar panel • Solar water heater • Electrical energy from solar energy Solar cell is a means for converting solar energy into electrical energy. This is a p-n junction diode.When solar energy falls onN side of a solar cell, a small electric current is obtained due to the flow of electrons to P region from N region. This phenomenon is the photovoltaic effect. It is the electrical energy thus obtained that is stored in batteries and used whenever necessary. The voltage and current obtained from a solar cell is insignificant. Alarge number of solar cells are suitably assembled to form a solarpanel. The electric current obtained from a large number of such cells can be stored in a battery and used asand when it is needed. The solar panel is usedextensively in lighting street lamps. They are used to meet the energy requirement of artificial satellites. Nowadays solar photovoltaic (SPV) power plants capable of producing electricity of thousands of kilowatt are in use. Heat energy from solar energy Let's do an experiment. Take two conical flasks. Paintthe outér surfaceof one with black paint and the other, with white paint. Fill both ofthem with water and expose them to direct sunlight

16 for the same period of time. Which one gets heated first? What may be the reason? Solar Cooker List down the specialities of a solar cooker by examining. • A box with blackened interior • A glass cover for the box • A mirror outside the boxWhat is the function of each? Find out the working of solar cookersother than the box type and record themin the science diary. Energy from wind Wind energy is a form of energy that is bothenvironment friendly and renewable. Electricity is obtained by turning the turbine of generator using the wind power. Here production of electricity does not incur any recurring expenditure. But it has certain limitations. This can be established only at those places where wind is available for most time oftheyear. We may require storage systems to use electricity when there is no wind. About 2 hectares of land is needed for the production of one megawatt power. The expense to establish a wind mill is veryhigh and that for repairing it in the event of damagescaused by heavy rain, cyclones, heat etc., is also very high.

17 Energy from sea Two third of the surface of the Earth is sea. Hence ocean is a major source of energy. Sea waves, high tide, heat from the ocean etc.,are the phenomena that we can make use of while producing energy from sea. Geo thermal energy Though the surface of the earth has cooled down making it habitable, the interior is still in the molten form. Magma, which is at a higher temperature, comes out of the core through itssofter regions. Such places are known as hot spots. Underground water at this place receivesheat energy from the hotspot and is converted into steam. Why is it said that geo thermal power plants are not possible inKerala? Discuss and record. Nuclear energy Look at the newspaper report carefully. Which is the disasterreported in the newspapers? How was it possible to produce such extremely devastatingenergy from an atom bomb? ……………………………………………………………………………………… Will it be possible to use this energy for peaceful purposes? Nuclear fission Nuclear fission isthe process by which the nuclei of greatermass are split into lighter

18 nuclei, using neutrons. The massofsmall nuclei formed islessthan that of parent nucleus. Itmeans that there is loss of matter during such a splitting. The matter that is lost is converted into energy. Accordingto Einstein's equation E = mc2, even if the matter convertedis very small, the energy produced will be very large. Uncontrolled fission will end in a huge explosion. This isthe processthattakes place in an atom bomb. There are power stations to control fission reaction and produce electricity. They are known asthermal power stations. Nuclear reactor is a system that converts nuclear energy into electrical energy. Enriched uranium is the fuel used in nuclear reactors. India has developed the indigenoustechnology of using carbide fuel in nuclearreactors. The power station at Kalpakkam in Tamilnadu makes use ofsuch a reactor. Dangerous radioactive radiations and products are also formed in nuclear reactions. What are the different methods by which energy is produced from the nucleus? ………………………………………………………………………… Renewable Sources of energy Now you are familiar with different sources of energy. Those whichreplenish energy as it is being used up are the renewable sources ofenergy. The natural sources of energy obtained from sunlight, wind, rain, high tide etc can be replenished. Hence these are examples for renewable sources of energy. They do not pollute the environment. Petroleum, coal, natural gases, nuclear energy etc., are non renewable

19 sources. They are harmful to the environment as well. Green Energy Green energy is the energy produced from natural sources that does not cause environmental pollution. All the energy produced from renewable sources belong to this category. The renewable sources like solar energy wind energy, energy from waves and energy from biomass are considered as green energy. Thisis also referred to as clean energy. But the energy produced from nonrenewable sources such as petroleum and coal, and the nuclear energy are named brown energy. These are sources which cause environmental problems including global warming. Classify the energy from the following sources as green energy andbrown energy: Solar cells, atomic reactors, tidal energy, hydroelectric power, diesel engines, windmills, thermal power stations. What must be done to ensure maximum utilization of green energywhile constructing a house? • Sufficient sunlight should be available in the rooms Green energy Brown energy

20 during daytime. • Comfortable warmth, coolness and air circulation must beavailable without the help of electricity. • Energy Crisis We have started using new energy sources besides conventionalones. Aren't we forced to face load shedding and power cut in spiteof all these? What may be the reason? Though the need for energy has increased manytimes production has not increased proportionally. 'Energy crisis is the consequence of increasing demand but decreasing availability' What can be done for reducing energy crisis as faras possible? Expand the list. • Judicious utilization of energy. • Maximumutilization ofsolar energy. • Minimising the wastage of water. • Making use of public transportation asfar aspossible. • Construction and beautifying of houses androadsin a scientific manner. • • • • Let us assess 1) In a way most of the important energy sources of today can be said tobe solar. Which of the following does not belong to solar energy?

21 a) fossil fuel b) energy from the wind c)nuclear energy d) biomass. 2)Which of the following is green energy? a) coal b) naphtha c)biogas d) petroleum gas 3) Write down the advantages and limitations of solar cooker. 4) Kerala has a long coastal land. Still ocean is not considered as a majorsource of energy. Why? 5) Find out the scope of hydrogen as a fuel with a high calorific value and prepare an essay. . Visit a hydroelectric power station and try to understand the different stages of the production of electricity. Make use of this principleand find out the scope of mini hydro electric power project ACTIVITY